Urca process

A cycle of nuclear reactions in which a nucleus loses energy by first absorbing
an electron and then reemitting a beta
particle (a high-speed electron) plus a neutrino-antineutrino
pair. It is an important process in pre-supernova
stars because, by cooling and decreasing the pressure in the star's core,
it renders the core unable to support the weight of the overlying layers.
These layers collapse onto the core and subsequently rebound and escape
in the supernova explosion. "Urca" is not an acronym but the name of a casino
in Rio de Janeiro at which George Gamow commented
to the Brazilian astrophysicist and art critic Mario Schenberg (1914-1990)
(who first pointed out the importance of neutrino emission in supernovae
to Gamow): "the energy disappears in the nucleus of the supernova as quickly
as the money disappeared at that roulette table." The process was dramatically
confirmed by Supernova 1987A whose
observation coincided with a burst of 11 neutrinos, detected by the the
Super-Kamiokande in Japan, and
a further eight registered independently by a detector in Ohio.